title: AMP N(1)-oxide, a unique compound of royal jelly, induces neurite outgrowth from PC12 cells via signaling by protein kinase A independent of that by mitogen-activated protein kinase.
abstract: Earlier we identified adenosine monophosphate (AMP) N(1)-oxide as a unique compound of royal jelly (RJ) that induces neurite outgrowth (neuritegenesis) from cultured rat pheochromocytoma PC12 cells via the adenosine A(2A) receptor. Now, we found that AMP N(1)-oxide stimulated the phosphorylation of not only mitogen-activated protein kinase (MAPK) but also that of cAMP/calcium-response element-binding protein (CREB) in a dose-dependent manner. Inhibition of MAPK activation by a MEK inhibitor, PD98059, did not influence the AMP N(1)-oxide-induced neuritegenesis, whereas that of protein kinase A (PKA) by a selective inhibitor, KT5720, significantly reduced neurite outgrowth. AMP N(1)-oxide also had the activity of suppressing the growth of PC12 cells, which correlated well with the neurite outgrowth-promoting activity. KT5720 restored the growth of AMP N(1)-oxide-treated PC12 cells. It is well known that nerve growth factor suppresses proliferation of PC12 cells before causing stimulation of neuronal differentiation. Thus, AMP N(1)-oxide elicited neuronal differentiation of PC12 cells, as evidenced by generation of neurites, and inhibited cell growth through adenosine A(2A) receptor-mediated PKA signaling, which may be responsible for characteristic actions of RJ.
authors.affiliation: Laboratory of Molecular Biology, Gifu Pharmaceutical University, Mitahora-higashi, Gifu 502-8585, Japan and Nagaragawa Research Center, API Co., Ltd, Nagara, Gifu 502-0071, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Hattori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nomoto
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Fukumitsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mishima
authors.forename: Shoei
authors.initials: S
authors.lastname: Furukawa